High Resolution And Parallel Numerical Simulation Of Explosion Phenomenon

Explosion phenomenon is one of the core issues of the design of new weapons.Simulation technology is one of the most effective methods to reveal and understandthe nature of explosion phenomenon, to study the transient evolution of explosionfield, and to investigate the propagation of blast wave. Parallel simulation technologywith high-order numerical scheme can significantly improve the accuracy andefficiency of the traditional numerical simulation, which is of great significance andbroad application prospects for the further improvement of national defense researchsystem.Combining RGFM with Level-set method for the material interface, this paperovercomes the nonphysical oscillations caused by the high-density ratio andhigh-pressure ratio material interface.3D air explosion and underwater explosion ofTNT and aluminized explosives were sucessfully simulated by solving Eulerequations based on the Fortran programming language. A fifth-order WENO finitedifference scheme was utilized for spatial discretization, and the third-order TVDRunger-Kutta method was used for time discretization. On this basis, a parallelizationmodule for structured grids was constructed based on MPI, and the parallelization of3D RGFM program was realized by calling this parallelization module, which hassignificantly improved the scale of simulation model.1）A solution for Riemann problem based on Euler equations was set up usingtwo-shock approximation procedure, Riemann problem consisting of detonationproducts and air (water) was solved as an example, JWL EOS was used for detonationproducts and stiff-gas EOS for air (water), the interface pressure, velocity and densityon both sides was obtained, which has laid a good foundation for simulating explosionphenomenon using RGFM method.2）An enclosed and portable data-passing module was set up based on MPI bysending and receiving data, which can realize the data exchange with all adjacentprocessors. We satisfy the special requirements for data communication encounterd inconstructing local Riemann problem by calling this module, and successfully realize the parallelization of3D RGFM code.3）3D air explosion of TNT and aluminized explosives were simulated usingparallel RGFM method, overpressure obtained by simulation was in good agreementwith that calculated by empirical formula, which indicates that RGFM method can beapplied to simulate the explosion phenomenon. Miller model was introduced todescribe the secondary energy release processe of aluminized explosive. Miller modeland Euler equations were coupled to simulate the whole process of air explosion ofaluminized explosive, and we also found that the overpressure of aluminizedexplosive attenuates slower than that of TNT.4）3D underwater explosion of TNT and aluminized explosives were simulatedusing parallel RGFM method. The entire process of bubble pulse was reappeared,maximum bubble radius and its arrival time were in good agreement with thetheoretical model, and the physical nature of the bubble pulsation was firstly revealedfrom the view of contact discontinuity movement in Riemann problem.